Image induction heating apparatus

- Canon
Skip to:  ·  Claims  ·  References Cited  · Patent History  ·  Patent History

Claims

1. An image heating apparatus comprising:

a rotational member having an electrically conductive layer;
an exciting coil for generating a magnetic flux, wherein the magnetic flux generated by said exciting coil generates eddy currents in said rotational member to make said rotational member generate heat, and an image on a recording medium being heated by the heat of said rotational member;
a magnetic member for guiding the magnetic flux generated by said exciting coil, wherein said magnetic member is provided inside of said rotational member to form a substantially closed magnetic circuit,
wherein an angle.theta. (rad) formed between a principle line of magnetic force directed from said magnetic member to said rotational member and a principle line of magnetic force directed from said rotational member to said magnetic member is determined to be 0<.theta.<.pi., and
wherein said magnetic member is provided in a half region of said rotational member.

2. An image heating apparatus according to claim 1, further comprising a half cylindrical guide member provided inside of said rotational member for guiding movement of said rotational member,

wherein said magnetic member is received in said guide member.

3. An image heating apparatus according to claim 2, wherein said exciting coil is received in said guide member.

4. An image heating apparatus according to claim 1, wherein said magnetic member has a first magnetic portion and a second magnetic portion through which each of said principle lines of magnetic force goes respectively.

5. An image heating apparatus according to claim 4, wherein an end portion of each of said first magnetic portion and said second magnetic portion is adjacent to said rotational member.

6. An image heating apparatus according to claim 4, wherein said second magnetic portion is provided upstream and downstream of said first magnetic portion with respect to a moving direction of said rotational member.

7. An image heating apparatus according to claim 6, wherein said exciting coil is wound around said first magnetic portion.

8. An image heating apparatus according to claim 4, further comprising a back-up member for forming a nip together with said rotational member,

wherein an end of said first magnetic portion is opposed to said nip.

9. An image heating apparatus according to claim 1, wherein.theta. satisfies the relation.pi./6<.theta.<5.pi./6.

10. An image heating apparatus according to claim 1, wherein.theta. is.pi./2.

11. An image heating apparatus according to claim 1, wherein said magnetic member is elongated in a direction perpendicular to a moving direction of said rotational member and said exciting coil is wound over a longitudinal direction of said magnetic member.

12. An image heating apparatus according to claim 1, wherein said rotational member is an endless film.

13. An image heating apparatus according to claim 1, further comprising a back-up member to form a nip together with said rotational member, wherein a recording medium which bears an unfixed toner image is nipped and conveyed at said nip to fix the unfixed toner image on the recording medium.

14. An image heating apparatus according to claim 1, wherein

said principle line of magnetic force directed from said magnetic member to said rotational member of said principle line of magnetic force directed from said rotational member to said magnetic member occur at the same time.

15. An image heating apparatus comprising:

a rotational member having an electrically conductive layer;
an exciting coil for generating a magnetic flux, wherein the magnetic flux generated by said exciting coil generates eddy currents in said rotational member and the eddy currents make said rotational member generate heat;
a back-up member for forming a nip together with said rotational member, wherein a recording medium which bears an image is nipped and conveyed at said nip, the image on the recording medium being heated by the heat of said rotational member; and
a magnetic member for guiding the magnetic flux generated by said exciting coil,
wherein said magnetic member is provided inside of said rotational member, said rotational member and said magnetic member form a substantially closed magnetic circuit, an angle.theta. (rad) formed between a principle line of magnetic force directed from said magnetic member to said rotational member and a principle line of magnetic force directed from said rotational member to said magnetic member is determined to be 0<.theta.<.pi., and a central portion of a heat region of said rotational member generated by said closed magnetic circuit is located upstream of said nip with respect to a moving direction of said rotational member.

16. An image heating apparatus according to claim 15, wherein said magnetic member has a first magnetic portion and a second magnetic portion each of which said principle line of magnetic force goes through respectively,

wherein said first magnetic portion, said second magnetic portion and said rotational member form a closed magnetic circuit.

17. An image heating apparatus according to claim 16, wherein said first magnetic portion is opposed to said nip.

18. An image heating apparatus according to claim 16, wherein said second magnetic portion is provided upstream and downstream of said first magnetic portion with respect to moving direction of said rotational member.

19. An image heating apparatus according to claim 18, wherein said exciting coil is wound around said first magnetic portion.

20. An image heating apparatus according to claim 15, wherein.theta. is preferably.pi./6<.theta.<5.pi./6.

21. An image heating apparatus according to claim 15, wherein.theta. is.pi./2.

22. An image heating apparatus according to claim 15, wherein said magnetic member is provided in the half region of said rotational member.

23. An image heating apparatus according to claim 22, further comprising a half cylindrical guide member provided inside of said rotational member for guiding movement of said rotational member,

wherein said magnetic member is received in said guide member.

24. An image heating apparatus according to claim 23, wherein said exciting coil is received in said guide member.

25. An image heating apparatus according to claim 15, wherein said magnetic member is elongated in a direction perpendicular to a moving direction of said rotational member and said exciting coil is wound over a longitudinal direction of said magnetic member.

26. An image heating apparatus according to claim 15, wherein said rotational member is an endless film.

27. An image heating apparatus according to claim 15, wherein a recording medium which bears an unfixed toner image is nipped and conveyed at said nip to fix the unfixed toner image on the recording medium.

28. An image heating apparatus according to claim 15, wherein

said principle line of magnetic force directed from said magnetic member to said rotational member and said principle line of magnetic force directed from said rotational member to said magnetic member occur at the same time.

29. An image heating apparatus comprising:

a rotational member having an electrically conductive layer;
an exciting coil for generating a magnetic flux, wherein the magnetic flux generated by said exciting coil generates eddy currents in said rotational member and the eddy currents make said rotational member generate heat, and an image on a recording medium being heated by the heat of said rotational member; and
a magnetic member provided inside of said rotational member for guiding the magnetic flux generated by said exciting coil, wherein said magnetic member has a first magnetic portion and a second magnetic portion which is provided in a direction substantially perpendicular to said first magnetic portion,
said first magnetic portion and said second magnetic portion are provided in the half region of said rotational member.

30. An image heating apparatus according to claim 29, further comprising a half cylindrical guide member provided inside of said rotational member for guiding movement of said rotational member,

wherein said magnetic member is received in said guide member.

31. An image heating apparatus according to claim 30, wherein said exciting coil is received in said guide member.

32. An image heating apparatus according to claim 29, further comprising a back-up member for forming a nip together with said rotational member,

wherein said first magnetic portion and said second magnetic portion are provided in the half region on the side of said nip of said rotational member.

33. An image heating apparatus according to claim 32, wherein said first magnetic portion is opposed to said nip.

34. An image heating apparatus according to claim 33, wherein said second magnetic portion is positioned at the first end of the first magnetic portion opposite to a second end facing to said nip.

35. An image heating apparatus according to claim 29, wherein said second magnetic portion is provided upstream and downstream of said first magnetic portion with respect to a moving direction of said rotational member.

36. An image heating apparatus according to claim 35, wherein said exciting coil is wound around said first magnetic portion.

37. An image heating apparatus according to claim 29, wherein ends of said first magnetic portion and said second magnetic portion are adjacent to said rotational member.

38. An image heating apparatus according to claim 29, wherein said rotational member, said first magnetic portion and said second magnetic portion form a substantially closed magnetic circuit.

39. An image heating apparatus according to claim 38, further comprising a back-up member for forming a nip together with said rotational member,

wherein a central portion of a heat region of said rotational member generated by said closed magnetic circuit is located upstream of said nip with respect to a moving direction of said rotational member.

40. An image heating apparatus according to claim 29, wherein said magnetic member is of a T-shaped form when seen with respect to a direction perpendicular to a moving direction of said rotational member.

41. An image heating apparatus according to claim 29, wherein said magnetic member is elongated in a direction perpendicular to a moving direction of said rotational member and said exciting coil is wound over a longitudinal direction of said magnetic member.

42. An image heating apparatus according to claim 29, wherein said rotational member is an endless film.

43. An image heating apparatus according to claim 29, further comprising a back-up member for forming a nip together with said rotational member, wherein a recording medium which bears an unfixed toner image is nipped and conveyed at said nip to fix the unfixed toner image on the recording medium.

44. An image heating apparatus comprising:

a rotational member having an electrically conductive layer;
an exciting coil for generating a magnetic flux, wherein the magnetic flux generated by said exciting coil generates eddy currents in said rotational member and the eddy currents make said rotational member generate heat, and an image on a recording medium is heated by the heat of said rotational member; and
a magnetic member provided inside of said rotational member for guiding the magnetic flux generated by said exciting coil,
wherein said magnetic member has a first magnetic portion and a second magnetic portion which is provided in a direction substantially perpendicular to said first magnetic portion, and said first magnetic portion and said second magnetic portion are rectangular parallelepiped, and both are independent of each other.

45. An image heating apparatus according to claim 44, further comprising a back-up member for forming a nip together with said rotational member,

wherein the end of said first magnetic portion is opposed to said nip.

46. An image heating apparatus according to claim 45, wherein said second magnetic portion is positioned at a first end of said first magnetic portion opposite to the second end facing to said nip.

47. An image heating apparatus according to claim 44, wherein said second magnetic portion is provided upstream and downstream of said first magnetic portion with respect to a moving direction of said rotational member.

48. An image heating apparatus according to claim 47, wherein said exciting coil is wound around said first magnetic portion.

49. An image heating apparatus according to claim 44, wherein end portions of said first magnetic portion and said second magnetic portion are adjacent to said rotational member.

50. An image heating apparatus according to claim 44, wherein said rotational member, said first magnetic portion and said second magnetic portion substantially form a closed magnetic circuit.

51. An image heating apparatus according to claim 50, further comprising a back-up member for forming a nip together with said rotational member,

wherein a central portion of a heat region of said rotational member generated by said closed magnetic circuit is located upstream of said nip with respect to a moving direction of said rotational member.

52. An image heating apparatus according to claim 44, wherein said magnetic member is of a T-shaped form when seen with respect to a direction perpendicular to a moving direction of said rotational member.

53. An image heating apparatus according to claim 44, wherein said first magnetic portion and said second magnetic portion are provided in the half region of said rotational member.

54. An image heating apparatus according to claim 53, further comprising a half cylindrical guide member provided inside of said rotational member for guiding movement of said rotational member,

wherein said magnetic member is received in said guide member.

55. An image heating apparatus according to claim 53, further comprising a back-up member for forming a nip together with said rotational member,

said first magnetic portion and said second magnetic portion are provided in the half region on the side of said nip of said rotational member.

56. An image heating apparatus according to claim 44, wherein said magnetic member is elongated in a direction perpendicular to a moving direction of said rotational member and said exciting coil is wound over a longitudinal direction of said magnetic member.

57. An image heating apparatus according to claim 44, wherein said rotational member is an endless film.

58. An image heating apparatus according to claim 44, further comprising a back-up member for forming a nip together with said rotational member,

wherein a recording medium which bears an unfixed toner image is nipped and conveyed at said nip to fix the unfixed toner image on the recording medium.
Referenced Cited
U.S. Patent Documents
4570044 February 11, 1986 Kobayashi et al.
4912514 March 27, 1990 Mitzutani
5153654 October 6, 1992 Yuminamochi et al.
5177549 January 5, 1993 Ohtsuka et al.
5278618 January 11, 1994 Mitani et al.
5331385 July 19, 1994 Ohtsuka et al.
5438398 August 1, 1995 Tanigawa et al.
5526103 June 11, 1996 Kato et al.
5552582 September 3, 1996 Abe et al.
5568240 October 22, 1996 Ontsuka
Foreign Patent Documents
0 649 072 April 1995 EPX
51-109737 September 1976 JPX
Other references
  • Patent Abstracts of Japan, vol. 11, No. 383 (P-646), 15 Dec. 1987 & JP 62-150371 (Alps Electric Co Ltd), 4 Jul. 1987.
Patent History
Patent number: 5881349
Type: Grant
Filed: Jul 11, 1997
Date of Patent: Mar 9, 1999
Assignee: Canon Kabushiki Kaisha (Tokyo)
Inventors: Hideo Nanataki (Tokyo), Hiroki Kisu (Fujisawa), Atsuyoshi Abe (Yokohama), Tetsuya Sano (Numazu)
Primary Examiner: Joan H. Pendegrass
Law Firm: Fitzpatrick, Cella, Harper & Scinto
Application Number: 8/891,976
Classifications
Current U.S. Class: By Heat And Pressure (399/328); By Heat (399/335); Printing Or Reproduction Device (219/216); Roller (e.g., Godet, Etc.) (219/619)
International Classification: G03A 1570;